Methods, materials and apparatus for treating bone and other tissue

ABSTRACT

A method of treating a vertebra, comprising:
         (a) accessing an interior of a vertebra; and   (b) introducing a sufficient amount of artificial biocompatible material which does not set to a hardened condition in storage, into said bone, with sufficient force to move apart fractured portions of said bone.

RELATED APPLICATIONS

The present application claims priority from Israel Application No.166017 filed on Dec. 28, 2004. The present application claims thebenefit under 35 USC 119(e) of U.S. Provisional Application No.60/592,149 filed on Jul. 30, 2004; 60/647,784 filed on Jan. 31, 2005 and60/654,495 filed on Feb. 22, 2005. The present application is also aContinuation-in-Part of PCT Application No. PCT/IL2004/000527 filed onJun. 17, 2004, which claims priority from Israel Application No. 160987filed on Mar. 21, 2004, and which claims the benefit under 35 USC 119(e)of the following U.S. Provisional Applications 60/478,841 filed on Jun.17, 2003; 60/529,612 filed on Dec. 16, 2003; 60/534,377 filed on Jan. 6,2004 and 60/554,558 filed on Mar. 18, 2004. The disclosures of all ofthese applications are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to structural enhancement of the humanbody, for example, by injection of a material which does not set to ahardened condition.

BACKGROUND OF THE INVENTION

A common occurrence in older persons is compression fractures of thevertebrae, causing both pain and a shortening (or other distortion) ofstature. One common treatment is vertebroplasty, in which cement isinjected into a fractured vertebra. While this treatment fixes thefracture and reduces pain, it does not restore the vertebra and personto their original height. Another problem is that the injected cementmay be injected out of the vertebra or may migrate out through cracks inthe vertebra. This may cause considerable bodily harm.

Another common treatment is kyphoplasty, in which the fracture isreduced, for example by first inflating a balloon inside the vertebraand then injecting a fixing material and/or an implant. The problem ofcement migration is reduced, but not avoided, as a lower pressure can beused to inject the cement.

Some fixing materials, such as polymethylmethacrylate (PMMA), emit heatand possibly toxic materials while setting. These may further weaken thebone and possibly cause the cement to loosen and/or the bone tofracture.

It has recently been suggested that some fixing materials, being harderthan bone, induce fractures in nearby bones.

It is also known to use bone-like repair materials, such as a slurry ofbone chips, which apparently do not induce such fractures. However,injecting such materials is difficult due to their viscosity. There havealso been attempts to reduce cement migration by injecting more viscouscement, for example, during the doughing time and the beginning ofpolymerization. However, the injection methods suggested require higherpressures for the more viscous material. Also, some types of viscousmaterials, such as hardening PMMA, have a small workability window athigh viscosities, as they harden very quickly once they reach a highviscosity. This has generally prevented very viscous materials and theassociated very high pressures from being used. One possible reason isthat as pressures increase, the physician is prevented from receivingfeedback on the resistance of the body to the injection of the cement.Thus, over-injection can easily occur.

Another way of increasing viscosity for injection is increasing amonomer-powder concentration ratio (MPR). However, it should be notedthat increasing a cement's MPR can lead to marked drops in some of itsmechanical properties, such as elastic modulus, yield strength andultimate strength.

US patents and U.S. Pat. Nos. 4,969,888, 5,108,404, 6,383,188,2003/0109883, 2002/0068974, U.S. Pat. Nos. 6,348,055, 6,383,190,4,494,535, 4,653,489 and 4,653,487, the disclosures of which areincorporated herein by reference describe various tools and methods fortreating bone. The present application is related to U.S. applicationSer. No. 09/890,172 (now U.S. Pat. No. 7,621,950) filed on Jul. 25, 2001and U.S. application Ser. No. 09/890,318 (now U.S. Pat. No. 7,097,648)filed on Jul. 25, 2001, the disclosure of which are incorporated hereinby reference.

SUMMARY OF THE INVENTION

An aspect of some embodiments of the invention relates to both movingand supporting bone using a same material, which is not enclosed by abag to prevent migration of the material. In an exemplary embodiment ofthe invention, a material which does not set to a hardened condition isinjected into a bone which is fractured and the pressure of the injectedmaterial moves the fractured pieces of the bone. The injected materialremains in the bone to provide support and prevent retrograde motion ofthe bone, for example, permanently or until the bone heals. Optionally,an additional material or implant may be provided to further support thebone, however, the injected material supports at least 20%, 30%, 40%,50% of the forces applied by the bone pieces, or smaller, intermediateor greater percentages. Optionally, the additional material is a cementwhich sets to a hardened condition.

In an exemplary embodiment of the invention, the material used is anartificial material. In an alternative embodiment of the invention, thematerial is natural.

In various embodiments of the invention, the following types ofmaterials are used:

(a) Relatively (to bone) soft solid materials which can optionallyundergo substantial plastic deformation without tearing and optionallyinclude no cross-linking above type I. In an exemplary embodiment of theinvention, these materials are compressed radially and provided througha narrow diameter aperture into the bone. In an alternative exemplaryembodiment of the invention, the material is provided in a small profilecondition and either compressed axially for loading into a deliverysystem or simply advanced into the bone without initial compression.

In an exemplary embodiment of the invention, the soft materials areplastically deforming materials. In the example of intra-vertebral use,at least 50%, 80%, 90%, 95% or more of deformation is optionally plasticdeformation. Optionally, the materials have an elastic deformation of0.1% or less. In an exemplary embodiment of the invention, for amaterial 1 mm in thickness, elastic spring-back is less than 0.1 mm,less than 0.05 mm or less.

(b) High viscosity fluids, such as bone slurry, semi-hardened cement andputty-like materials. These materials are flowed through the deliverysystem, optionally under a high pressure. In some cases, the fluids setto a hardened condition, for example, due to a polymerization process ordue to contact with body fluids.

An aspect of some embodiments of the invention relates to fracturereduction (e.g., height restoration in a vertebra), using a softmaterial that is not constrained by an enclosure. In an exemplaryembodiment of the invention, the material is a soft material softer than60A, 70A, 80A, 90A or 100A shore. Optionally, the material is at least10A shore or 20A shore, for example, at least 20A or 30A shore.

In an alternative exemplary embodiment of the invention, the material isa flowable material, for example, with a viscosity greater than 100Pascal-second, 300 Pascal-second, 500 Pascal-second, 600 Pascal-second,800 Pascal-second, 1000 Pascal-second or more. Optionally, the materialhas a viscosity of less than 4,000 Pascal-second, optionally less than1,800 Pascal-second, optionally less than 1,400 Pascal-second,optionally less than 1,100 Pascal second or smaller intermediate orlarger values.

An aspect of some embodiments of the invention relates to the use ofmaterials which do not set to a hardened condition for supporting bone.In an exemplary embodiment of the invention, the material is injectedinto a bone.

As used herein, the term “setting” is used to define materials whosemechanical properties, such as strength and/or hardness, increase forchemical reasons, for example, due to polymerization during and/orshortly after implantation, e.g., after a few hours, a few days or a fewweeks. It should be noted that a material which sets to a non-hardenedcondition is a setting material. A pre-set soft material will alsogenerally not set to a hardened condition.

As used herein the term “hardened condition” is used to describematerials that are 50% or more the hardness of cortical bone. In somecases it is desirable to compare the strength and/or young modulous ofthe material to cortical and/or trabecular bone, in which case, valueswithin 110% or 120% or 130% or intermediate values of the values for thebone in question bone may be desirable.

In an exemplary embodiment of the invention, the injected material isselected to have a high viscosity or is a soft material which canundergo plastic deformation, for example, by the material not tearingduring an injection via a small diameter tube. Optionally, the materialis mechanically sheared during injection.

In an exemplary embodiment of the invention, the use of a non-hardeningmaterial allows more flexibility in injection methods, due to therelieving of time constraints typically involved in using a cement whichsets to a hardened condition, such as PMMA, in which the time betweenmixing and setting and especially the time at a given viscosity range,constrains the physician. Optionally, a non-hardening material is moreconvenient to use, as it does not require the user to mix the materialat the time of use. In an exemplary embodiment of the invention, thematerial is provided in a pre-loaded magazine or delivery system.

A potential property of using a viscous or soft solid material is thatthere is less danger of leakage out of the vertebra. Optionally, variouscomponents are added to the material, for example, a bone growth factoror a radio-opaque material.

A potential advantage of some pre-set or non-setting materials is thatan exothermic setting reaction is avoided.

In an exemplary embodiment of the invention, the injected material isfree of cross-linking or includes only type I cross-linking.

Optionally, the injected material softens over time.

In an exemplary embodiment of the invention, the material is formulatedso that only hardens in the presence of water or other materials commonin the body but does not set or harden outside the body. Thus thematerial can be pre-formulated and mixed and will only set after beingintroduced into the body. Optionally, the material sets after 10-30minutes or longer.

An aspect of some embodiments of the invention relates to treatment ofbody tissues by injecting a non-solid or soft-solid material harder than10A shore. In an exemplary embodiment of the invention, the injectedmaterial flows into or is forced into an intra-body space to be filledthereby. In an exemplary embodiment of the invention, the injectedmaterial is viscous enough or solid enough so it does not inadvertentlymigrate out of a tissue into which it is injected, for example, out of avertebra. This viscosity level used may depend on the size and/or shapeof voids leading out of the tissue being treated. Optionally, thematerial sets to a hardened condition. Alternatively, the material doesnot.

In an exemplary embodiment of the invention, the material is providedunder a pressure of greater than 40 atmospheres.

An aspect of some embodiments of the invention relates to a method ofproviding a flowable or soft-solid material into the body, in discreteunits, optionally of predetermined quantities. In an exemplaryembodiment of the invention, a delivery system with a first quantity ofmaterial is provided and a user can select a discrete amount of thisfirst quantity to be injected. This is in contrast to continuous methodsin which material is injected until a user stops the injection or thematerial is all used up. Optionally, the material to be injected isprovided in a magazine from which a unit of material can be selected forinjection. Optionally, selection is by cutting the material away fromthe magazine.

In an exemplary embodiment of the invention, a treatment for a bone isprovided by injecting two, three, four or more discrete units ofmaterial.

A potential advantage of working in discrete portions which areconsiderably smaller than a total therapeutic amount, in someembodiments of the invention, is that a friction between the materialand a delivery system is reduced, as the amount of material advanced ateach time is reduced.

An aspect of some embodiments of the invention relates to using a sleevefor delivering material or a device implant that have a high friction toa delivery system, to a site inside the body. In an exemplary embodimentof the invention, the sleeve is designed to reduce friction between thedelivered material and a delivery system. Optionally, the sleeve isprovided inside of a delivery tube. Optionally, force is applieddirectly on the sleeve to deliver the material or implant.

An aspect of some embodiments of the invention relates to a system fordelivering material into a bone which system is adapted to travel over aguidewire. Optionally, the system travels over a guidewire when loaded.Alternatively or additionally, the system is loaded after beingintroduced into the body. In an exemplary embodiment of the invention,the system comprises a distal end adapted to penetrate bone, for examplevertebral bone. In an exemplary embodiment of the invention, the systemis adapted to deliver the material into a vertebra in a manner whichwill at least partially restore a height of said vertebra. In anexemplary embodiment of the invention, the material surrounds theguidewire.

An aspect of some embodiments of the invention relates to a system fordelivering material into a bone under pressure, the system being adaptedto penetrate bone. In an exemplary embodiment of the invention, thesystem comprises a distal tip adapted to penetrate bone. Optionally, anaperture is formed near the distal tip for delivering of said material.

An aspect of some embodiments of the invention relates to materials foruse in the body for supporting hard tissue and which do not set to ahardened condition when in storage (e.g., for over 1 hour or over oneday or 1 week). In an exemplary embodiment of the invention, thematerial comprises polymers without cross-linking or with type Icross-linking. Optionally, the composition of the material is a mixtureof Laurylmethacrylate (LMA) and methylmethacrylate (MMA), for example ina ratio of between 90:10 and 10:90. Optionally, the material isthermoplastic rather than thermosetting.

In an exemplary embodiment of the invention, the material is aputty-like material. In one example, the material is composed of amixture of hydroxyapatite and sufficient sodium alginate, such that themixture remains putty like after time, at least if not in contact withwater.

In an exemplary embodiment of the invention, the material softens overtime. Optionally, the material is composed of MMA and LMA with poly-HEMAadded, and softens by the absorption of body fluids by the composition.

Alternatively or additionally, water soluble materials, such as salts ormaterials which degrade in body fluids, such as some sugars andplastics, are added and when they degrade, soften the material.

In an exemplary embodiment of the invention, the material hardens overtime, but does not harden completely. Optionally, the material includesa solvent, such as NMP (N-methyl pyrolidone), which is soluble in waterand as it is carried away, the material hardens somewhat.

Optionally, the actually injected material includes one or more addedcomponents. Optionally, one or more of a radio opaque marker,antibiotic, anti-inflammatory and/or bone growth factor, are provided asthe added components. Optionally, an added component is added by volumeof less than 30% of the material volume and in total less than 50% forall the added components.

Optionally, the added materials are chemically inert but may have astructural effect, for example, due to bulk thereof.

Optionally, non-inert materials are added, for example, 5% of a cementwhich sets to a hardened condition may be added. Optionally, suchnon-inert materials are mixed-in at a coarse grain.

An aspect of some embodiments of the invention relates to using amaterial which sets to a hardened condition, which maintains a highviscosity value during a substantial window of time. In an exemplaryembodiment of the invention, the viscosity is between 600 Pascal-secondand 1,800 Pascal-second during a period of at least 5 or at least 8minutes. In an exemplary embodiment of the invention, the material iscomposed of a mixture of PMMA beads and/or styrene beads and MMAmonomers, with the increase in viscosity being provided by the size ofthe beads of, for example, 10-200 microns and/or by changing the ratiobetween beads and liquid MMA monomer. Optionally, as setting progresses,viscosity due to the beads is replaced/increased by viscosity due to thepolymerization process.

An aspect of some embodiments of the invention relates to treatingcompression fractures by heating a compressed vertebra. Optionally, theheating is provided by a stand-alone tool. Optionally, the heating isprovided to replace heating which is otherwise provided by the settingof a cement. Optionally, a thermocouple or other temperature sensor isused to control the amount of heating provided.

An aspect of some embodiments of the invention relates to a method ofselecting mechanical properties of an implant to match those of a bone,cortical and/or trabecular, being treated. In an exemplary embodiment ofthe invention, one or more of hardness, strength and/or Young modulusare matched.

There is thus provided in accordance with an exemplary embodiment of theinvention, a method of treating a vertebra, comprising:

(a) accessing an interior of a vertebra; and

(b) introducing a sufficient amount of artificial biocompatible materialwhich does not set to a hardened condition in storage, into said bone,with sufficient force to move apart fractured portions of said bone.

Optionally, said material does not set to a hardened condition afterintroduction into the body.

In an exemplary embodiment of the invention, said material can be storedfor over 1 day.

In an exemplary embodiment of the invention, said material softens afterimplantation.

In an exemplary embodiment of the invention, said material partlyhardens after implantation.

In an exemplary embodiment of the invention, said material does set to ahardened condition after introduction into the body.

In an exemplary embodiment of the invention, said material does not setto a hardened condition in storage.

In an exemplary embodiment of the invention, said material isartificial.

In an exemplary embodiment of the invention, said material is aplastically deforming material. Optionally, said material has a hardnessof between 10A shore and 100A shore. Alternatively or additionally, saidmaterial is free of cross-linking higher than type I. Alternatively oradditionally, said material is thermoplastic. Alternatively oradditionally, said material comprises LMA (lauryl methacrylate) and MMA(methyl methacrylate).

In an exemplary embodiment of the invention, said material is a viscousfluid. Optionally, said material has a viscosity between 600Pascal-second and 1,800 Pascal-second.

In an exemplary embodiment of the invention, introducing comprisesintroducing at a pressure of at least 40 atmospheres.

In an exemplary embodiment of the invention, introducing comprisesintroducing at a pressure of at least 100 atmospheres.

In an exemplary embodiment of the invention, introducing comprisesintroducing through a delivery channel having a diameter of less than 6mm and a length of at least 70 mm.

In an exemplary embodiment of the invention, introducing comprisesintroducing through an extrusion aperture having a minimum dimension ofless than 3 mm.

In an exemplary embodiment of the invention, introducing comprisesintroducing through an extrusion aperture having a minimum dimension ofless than 1.5 mm.

In an exemplary embodiment of the invention, introducing comprisesintroducing through a plurality of extrusion apertures simultaneously.

In an exemplary embodiment of the invention, introducing compriseschanging an introduction direction during said introduction.

In an exemplary embodiment of the invention, introducing compriseschanging an introduction position during said introduction.

In an exemplary embodiment of the invention, said material comprises atleast one material adapted to function in a capacity other thanstructural support.

In an exemplary embodiment of the invention, introducing comprisesadvancing said material using a motor.

In an exemplary embodiment of the invention, introducing comprisesadvancing said material using a hydraulic source.

In an exemplary embodiment of the invention, introducing comprisesintroducing said material in discrete unit amounts. Optionally, at leastsome of the units have different mechanical properties form each other.

In an exemplary embodiment of the invention, introducing comprisescutting said material away from a delivery system.

In an exemplary embodiment of the invention, introducing comprises nottwisting said material during said introducing.

In an exemplary embodiment of the invention, introducing comprisesshaping an extrusion form of said material using an exit aperture.

In an exemplary embodiment of the invention, accessing comprisesaccessing using a guidewire and providing a delivery system over theguidewire.

In an exemplary embodiment of the invention, accessing comprisesaccessing using a delivery system of said material.

In an exemplary embodiment of the invention, introducing comprisesintroducing without a separate void forming act.

In an exemplary embodiment of the invention, introducing comprisesintroducing without a spatially constraining enclosure.

In an exemplary embodiment of the invention, introducing comprisesintroducing in a spatially constraining enclosure.

In an exemplary embodiment of the invention, introducing comprises alsointroducing at least 10% by volume of a material which sets to ahardened condition.

In an exemplary embodiment of the invention, the method comprisesselecting said material to have at least one of hardness and Youngmodulus properties less than those of trabecular bone of said vertebra,after a week from said implantation.

In an exemplary embodiment of the invention, said introduced material isoperative to support at least 30% of a weight of vertebra within a weekafter implantation.

There is also provided in accordance with an exemplary embodiment of theinvention, a surgical set comprising:

at least one tool adapted to deliver a material into a vertebra; and

at least 1 cc of artificial biocompatible prepared material that doesnot set to a hardened condition outside the body. Optionally, said atleast one tool comprises a pressure delivery mechanism capable ofdelivering said material at a pressure of above 100 atmospheres.Alternatively or additionally, said set comprises a disposable hydraulicactuator. Alternatively or additionally, said set comprises areplaceable magazine for storing said material.

There is also provided in accordance with an exemplary embodiment of theinvention, a method of treating bone, comprising:

(a) accessing an interior of a bone; and

(b) introducing a sufficient amount of biocompatible material into saidbone, without an enclosure between said material and the bone, saidintroducing being with sufficient force to move apart fractured portionsof said bone. Optionally, the method comprises leaving said material insaid bone to resist at least 30% of a normative force which urges saidportions together.

Optionally, said bone is a vertebra. Optionally, said material does notset to a hardened condition in storage. Alternatively or additionally,said material does not set to a hardened condition in the body.

There is also provided in accordance with an exemplary embodiment of theinvention, a method of treating a vertebra, comprising:

(a) accessing an interior of a vertebra; and

(b) introducing a sufficient amount of spatially unconstrainedbiocompatible soft material having a hardness of less than 100A Shoreinto said vertebra, with sufficient force to move apart fracturedportions of said bone.

There is also provided in accordance with an exemplary embodiment of theinvention, a surgical set comprising:

at least one tool adapted to deliver a material into a vertebra; and

at least 1 cc of biocompatible prepared material that has a Youngmodulus of less than 120% of healthy vertebral trabecular bone and isprepared at least 1 day ahead of time.

There is also provided in accordance with an exemplary embodiment of theinvention, a method of treating a bone, comprising:

(a) accessing an interior of a bone; and

(b) introducing, via a delivery tube, into said bone an unconstrainedplastically deformable solid material harder than 10A shore and softerthan 100A shore.

There is also provided in accordance with an exemplary embodiment of theinvention, apparatus for delivering a material or an implant into abone, comprising:

(a) a delivery tube having a lumen and a distal end adapted forinsertion into a body;

(b) a payload comprising at least one of material and an implant insidesaid lumen;

(c) a lining disposed between said tube and said payload; and

(d) an advancing mechanism adapted to move said liner and said payloadto said distal end,

wherein said liner reduces a friction of said payload against saiddelivery tube. Optionally, the apparatus comprises a splitter whichsplits said sleeve.

In an exemplary embodiment of the invention, said mechanism pulls saidsleeve.

In an exemplary embodiment of the invention, said mechanism pushes saidpayload.

In an exemplary embodiment of the invention, said sleeve folds over saiddelivery tube.

There is also provided in accordance with an exemplary embodiment of theinvention, a biocompatible material which does not set to a hardenedcondition and does not include cross-linking of a type greater than typeI and formed of MMA (methyl methacrylate). Optionally, said material isformed of a mixture of MMA and LMA (lauryl methacrylate)

There is also provided in accordance with an exemplary embodiment of theinvention, a second medical use of PMMA for height restoration ofvertebral bones when applied directly into a vertebra. Optionally, saidPMMA is applied during setting while at a viscosity higher than 400Pascal-second.

There is also provided in accordance with an exemplary embodiment of theinvention, a second medical use of bone putty for vertebral treatmentwhen applied under pressure through a tubular delivery system into avertebral bone.

There is also provided in accordance with an exemplary embodiment of theinvention, a polymerizing composition, comprising:

(a) a first quantity of beads having a set of sizes; and

(b) a second quantity of monomer,

wherein said quantities are selected so that a mixture of saidquantities results in a setting material having a workability window ofat least 5 minutes at a viscosity between 500 and 2000 Pascal-second.

There is also provided in accordance with an exemplary embodiment of theinvention, a method of treating bone, comprising providing a heat sourceinto a vertebra in a controlled manner.

There is also provided in accordance with an exemplary embodiment of theinvention, a composite tool for accessing bone, comprising:

an elongate body having:

-   -   (a) a head adapted to penetrate bone;    -   (b) an aperture adapted to extrude material into bone, near said        head; and    -   (c) a lumen adapted to deliver material to said aperture; and

a source of material under pressure. Optionally, the tool comprises alumen for a guidewire.

There is also provided in accordance with an exemplary embodiment of theinvention, a composite tool for accessing bone comprising:

a drill tool including a lumen;

a separable guidewire adapted to fit in said lumen; and

a handle adapted to control the relative positions of said drill tooland said guidewire.

BRIEF DESCRIPTION OF THE FIGURES

Exemplary non-limiting embodiments of the invention will be describedwith reference to the following description of embodiments inconjunction with the figures. Identical structures, elements or partswhich appear in more than one figure are generally labeled with a sameor similar number in all the figures in which they appear, in which:

FIG. 1A is a general flowchart of a process of treating a compressionfracture, in accordance with an exemplary embodiment of the invention;

FIG. 1B is a more detailed flowchart of a process of treating acompression fracture, in accordance with an exemplary embodiment of theinvention;

FIG. 2 shows a composite tool for accessing a vertebra, in accordancewith an exemplary embodiment of the invention;

FIGS. 3A-3F show stages of a method of treatment according to FIGS. 1Aand 1B, in an exemplary implementation of the method;

FIGS. 4A and 4B illustrate basic material delivery systems, inaccordance with exemplary embodiments of the invention;

FIGS. 5A and 5B show details of material extruder tips, in accordancewith exemplary embodiments of the invention;

FIG. 5C shows an elongated and curved extrusion of material, inaccordance with an exemplary embodiment of the invention;

FIGS. 6A-6C illustrate narrowing lumen sections of a delivery system, inaccordance with an exemplary embodiment of the invention;

FIG. 7A illustrates a hydraulic delivery system, in accordance with anexemplary embodiment of the invention;

FIGS. 7B and 7C show alternative methods of providing hydraulic power tothe system of FIG. 7A, in accordance with exemplary embodiments of theinvention;

FIGS. 7D and 7E illustrate an exemplary hydraulic system including adisposable unit, in accordance with an exemplary embodiment of theinvention;

FIG. 8A shows a cassette based delivery system, in accordance with anexemplary embodiment of the invention;

FIG. 8B is a detail showing the delivery of unit element, in accordancewith an exemplary embodiment of the invention;

FIGS. 9A and 9B show a material pusher with reduced material twisting,in accordance with an exemplary embodiment of the invention;

FIGS. 10A-10F show sleeve based material pushers, in accordance withexemplary embodiments of the invention;

FIGS. 11A and 11B show squeeze based delivery systems, in accordancewith exemplary embodiments of the invention;

FIGS. 12A, 12B, and 12D illustrate a one step access and deliverysystem, in accordance with an exemplary embodiment of the invention;

FIG. 12C shows an over-the-wire delivery system, in accordance with anexemplary embodiment of the invention; and

FIG. 13 is a graph showing compressibility of a material in accordancewith an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Overview of Exemplary Process

FIG. 1A is a general flowchart 100 of a process of treating acompression fracture, in accordance with an exemplary embodiment of theinvention.

At 102, a bone to be treated is identified. In the case of a vertebra,this usually involves X-ray or CT images to identify a vertebra or otherbone that is fractured, for example by a compression fracture. Thefollowing description focuses on vertebral compression fractures butsome embodiments of the invention are not limited to such cases.

In an exemplary embodiment of the invention, the access is minimallyinvasive, for example, only a single channel is formed into the body.Optionally, the procedure is carried out via a cannula having a diameterof, for example of 5 mm, 4 mm or less in diameter is inserted into thebody. In some cases, multiple openings into the body are formed. Theprocedure can also be carried out using a surgical or key-hole incision,however, this may require a longer recuperation period by the patient.Optionally, the cannula (and corresponding length of a delivery tubedescribed below) is at least 50 mm, 70 mm, 100 mm or more orintermediate or smaller values.

At 104, the vertebra is accessed.

At 106, a material, having a high viscosity in some embodiments of theinvention, is injected into the vertebra.

At 108, material is optionally provided in a manner and/or amount whichrestores at least part of the height of the vertebra, for example, 20%,40%, 50% or intermediate or a higher percentage of a pre-compressionheight. A particular feature of some embodiments of the invention isthat the provided material is of sufficient viscosity or sufficientlysolid that leakage from the vertebra is reduced or prevented, ascompared to liquid PMMA cement. A pressure used to advance the materialmay be higher than what is known in the art to match the increasedviscosity.

At 110, the procedure is completed and the tube is removed.

Exemplary Bone Access Set

Before going into the details of the procedure, the tools used are firstdescribed. FIG. 2 shows a composite tool 200 optionally used foraccessing the bone, in accordance with an exemplary embodiment of theinvention. In an exemplary embodiment of the invention, the access toolsused comprise a set of component tools that interlock to act,selectively, as a single tool or as separate tools. In an exemplaryembodiment of the invention, this composite set/tool serves as a onestep access system in which only a single insertion of objects into thebody is required. Optionally, as described below, the delivery system isalso inserted at the same time. Optionally, a cannula portion of thetool is omitted, for example as described in the embodiments of FIGS.12A-12C.

In an exemplary embodiment of the invention, the components of tool 200are coaxially matched components, which fit one within the lumen of thenext.

An optional cannula 202 comprises a handle 204 and a body including alumen.

An optional drill tool 206 includes an elongate body adapted fordrilling and a handle 208. Optionally, handle 208 selectivelyrotationally locks to handle 204, for manipulation using a single hand,optionally using a snap-lock 217. The body of tool 206 fits in the lumenof cannula 202. Optionally, a section 210 of tool 206 is marked to bevisible on an x-ray image, even in contrast to cannula 202. Optionally,this allows the difference in diameters between cannula 202 and drilltool 206 to be minimal. Absent such a marker, in some cases, thedifference in diameters may not be visible on an x-ray image and the twotools cannot be distinguished.

An optional guidewire 212 is provided inside a lumen of drill tool 206.Optionally, a knob or other control 214 is provided for selectiveadvancing and/or retracting of guidewire 212 relative to drill 216. Theknob may be marked with relative or absolute positions.

Optional depth marking are provided on cannula 202.

An exemplary use of these tools will be described below, in which FIGS.3A-3F schematically show the progress as a vertebra 300 having acompression fracture 306 is being treated, paralleling a detailedflowchart 120 shown in FIG. 1B.

Penetrate to Bone

At 122 (FIG. 1B), a passage is formed to the bone through a skin layer312 and intervening tissue, such as muscle and fat. Optionally, thepassage is formed by advancing composite tool/set 200 until a tip 218 ofguidewire 212 contacts the bone. In some embodiments, tip 218 isdesigned to drill in soft tissue (e.g., includes a cutting edge).Alternatively or additionally, tip 218 includes a puncturing pointadapted to form a puncture in soft tissue.

This is shown in FIG. 3A. Also shown are cortical plates 302 and 304 ofthe vertebra and a cancellous bone interior 308.

A single pedicle 310 is shown, due to the view being cross-sectional.Optionally, the access to the vertebra is via a pedicle. Optionally, theaccess is via both pedicles. Optionally, an extrapedicular approach isused. Optionally, the access point or points are selected to assist inan even lifting of the vertebra.

Penetrate Bone

At 124, tip 218 penetrates through the cortex of the bone being treated(FIG. 3B). In an exemplary embodiment of the invention, tip 218 isseparately manipulated from the rest of composite tool 200. Optionally,tip 218 is advanced until it contacts a far side of the vertebra.

In an exemplary embodiment of the invention, tip 218 of guidewire 212 isformed to drill in bone and is advanced through the vertebral cortex byrotation or vibration. Optionally, it is advanced by tapping thereon orapplying pressure thereto.

Optionally, a relative position of the guidewire and the cannula isnoted, to assist in determining the inner extent of the vertebra.

At 126, the guidewire is optionally retracted. Optionally, the guidewireis axially locked to drill tool 206. Optionally, guidewire 212 and drilltool 206 align so that tip 218 and a tip 216 of the drill tool form asingle drilling tip.

At 128, drill tool 206 is advanced into the bone (FIG. 3C). Optionally,tip 216 of drill tool 206 designed for drilling and/or is advanced, forexample, by tapping, rotation and/or vibration. Optionally, the drilltool is advanced to the far side of the vertebra. Optionally, theprevious depth marking of the guidewire is used to limit this advance.Optionally, the guidewire is not retracted at 126. Instead, drill tool206 is advanced over the guidewire until it reaches the end of theguidewire.

At 130, cannula 202 is optionally advanced to the bone over the drill.Optionally, the leading edge of the cannula is threaded or otherwiseadapted to engage the bone at or about the bore formed by the drilltool. Optionally, the cannula is inserted into the bone.

At 132, the guidewire and/or drill tool are optionally removed (FIG.3D).

In some embodiments, the cannula is not advanced all the way to thebone. In others, the cannula may be advanced into the bone, for example,to prevent contact between the treatment and cortical bone and/or weakor fractured bone. Optionally, the cannula is advanced past the pedicleand to the vertebral interior 308.

Optionally, a reamer (not shown) is inserted into the cannula and usedto remove tissue from interior 308.

Inject Material

At 134, a material delivery system 314 is provided into cannula 202(shown in FIG. 3E). Optionally, the delivery system delivers material toa side thereof (described below).

At 136, system 134 is activated to inject material 316 into interior308. FIG. 3E shows that when enough material is injected, vertebralheight may be partially or completely restored. The injected materialmay partially or completely compress interior 308.

Feedback

At 138, feedback is optionally provided to an operator, to decide ifinjection is completed. Optionally, feedback is provided by fluoroscopicimaging of the site. However, other imaging methods may be used.

Optionally, non-imaging feedback is provided, for example a pressureinside the vertebra, using a pressure sensor (not shown), or using anindicator (visual or audio) for the amount of material injected.

Optionally, the feedback is used to decide if the procedure isprogressing as desired, e.g., desired amount of height restoration (ifany), verify a lack of material leakage, determine symmetry or asymmetryand/or the presence of new fractures in bone.

Repeat and/or Change

Optionally, the material is provided in a magazine having a fixed amount(described below). If that magazine is finished and additional materialis required, a refill may be provided (140), for example by replacingthe magazine with a new one.

Optionally, a property of the delivery of material is changed, forexample one or more of a delivery pressure, a delivery rate, an amountof delivery when delivery is in discrete units, a viscosity, compositionand/or type of the delivered material, a pre-heating or pre-cooling ofthe material, a location of provision inside the vertebra, a spatialpattern of provision and/or a direction of provision in the vertebra.

Optionally, the direction of provision of the material is changed (142),for example, to assist in maintaining symmetry of lifting or to point inthe injection of material away from a fracture or towards an emptyspace. Optionally, the direction of provision is changed by rotatingdelivery system 314. Alternatively or additionally, injection iscontinued through a new access hole in the vertebra. Optionally, thecannula is moved axially.

Optionally, a different material is used to top off the procedure, forexample, a cement which sets to a hardened condition (e.g., PMMA) isused to seal the entry hole and/or stiffen the non-hardening material(144).

Complete Procedure

At 146, the tools are removed. FIG. 3F shows vertebra 300 after theprocedure is completed. Optionally, the entry incision is sealed, forexample, using tissue glue or a suture.

Exemplary Basic Delivery System

FIGS. 4A and 4B illustrate basic delivery systems, in accordance withexemplary embodiments of the invention

FIG. 4A is a cross-sectional view of a delivery system 400, comprisinggenerally of a delivery tube 402 having one or more extrusion apertures404. Optionally, the distal end of tube 402 is sealed. Alternatively itmay be at least partially open, so forward injection of material isprovided. It is noted that when the end is sealed, there may be lessforce acting to retract the delivery system from the vertebra. Materialinside tube 402 is advanced by a threaded pusher 406.

In the design shown, tube 402 is attached to a barrel 408 with apermanent or temporary attachment method. Threading (not shown) may beprovided inside of barrel 408, to match the threading on pusher 406.Alternatively (not shown), the inner diameter of barrel 408 is greaterthan that of tube 402. Optionally, barrel 408 and/or tube 402 serve as areservoir of material.

A body 410 which acts as a nut and includes an inner threading engagespusher 406. In an exemplary embodiment of the invention, when a handle412 of pusher 402 is rotated (while holding on to body/nut 410), pusher406 is advanced, injecting material out of apertures 404 into the body.Optionally, barrel 408 is detachable from body 410, for example, forreplacing barrel 408 with a material-filled barrel, when one barrel isemptied. The coupling can be, for example, a threading or a quickconnect, for example, a rotate-snap fit. Optionally, tube 402 isdetachable from barrel 408, for example using the same type of coupling.

In an exemplary embodiment of the invention, when the distal tip ofpusher 406 goes past apertures 404 (in embodiments where it is thatlong), the passage cuts the material in front of the pusher away fromthe material exiting the aperture, releasing the exiting material fromthe delivery system.

FIG. 4B shows an alternative embodiment of a delivery system, 420, inwhich a different design of apertures 424 is used. In the embodiment, adelivery tube 422 serves as a barrel and storage for the material and isoptionally detachable from a threaded nut body 430. Optionally, tube 422is long enough to include an amount of material sufficient forinjection, for example, 8-10 cc. Optionally, body 430 includes a pistolor other grip (not shown) and, as above, may be threaded to engage apusher 426.

In an exemplary embodiment of the invention, the delivery system is madeof metal, for example, stainless steel. Alternatively or additionally,at least some of the components are made of a polymer material, forexample, PEEK, PTFE, Nylon and/or polypropylene. Optionally, one or morecomponents are formed of coated metal, for example, a coating withTeflon to reduce friction.

In an exemplary embodiment of the invention, the threading of the pusheris made of Nitronic 60 (Aramco) or Gall-Tough (Carpenter) stainlesssteels.

In an exemplary embodiment of the invention, instead of a standardthreading, a ball screw is used. Optionally, the use of a ball screwincreases energy efficiency and makes operation easier for manualsystems as shown in FIGS. 4A and 4B. Optionally, a gasket is provided toseparate the balls from the material.

In an exemplary embodiment of the invention, the delivered material isprovided as an elongate sausage with a diameter similar to that of thedelivery tube and/or aperture(s). Optionally, a long delivery tube isprovided. Alternatively, a plurality of such strings/sausages areimplanted. Optionally, the material is provided in a diameter smallerthan that of the delivery tube, for example, 0.1-0.01 mm smaller so thatthere is reduced friction.

Exemplary Extrusion Details

Referring back to FIG. 4A, it is noted that the more proximal extrusionaperture 404 is optionally smaller than the more distal one. Optionally,the relative sizes are selected so that the extrusion rate and/or forcesat the two holes is the same. Alternatively, the holes are designed sothat the rates and/or forces are different. Referring to FIG. 4B, threeaxially spaced apertures may be provided and the profile of extrusioncan be that a greatest extrusion and/or force is applied at the middlehole.

In an exemplary embodiment of the invention, the sizes of apertures areselected so that the total amount of material ejected is as desired,taking into account the possible sealing of some of the apertures by theadvance of the pusher.

In an exemplary embodiment of the invention, the apertures are designedso that the extruded material is ejected perpendicular to the deliverysystem. Optionally, the delivery system is shaped so that the ejectionis at an angle, for example, an angle in the plane of the axis and/or anangle in a plane perpendicular to the axis. Optionally, the angle isselected to offset forces which tend to push the delivery system out ofthe vertebra. Alternatively or additionally, the angle is selected tomatch a desired lifting direction of the vertebra or, for example, toprevent direct lifting by the extruded material. Optionally, thedelivery system is inserted at a desired angle into the vertebra.Optionally, the angles of different apertures, for example, apertures onopposite sides of the delivery tube, are different, for example,defining a 180 degree angle between the apertures on opposite sides or amore acute (towards the proximal side) or oblique angle. In an exemplaryembodiment of the invention, the extrusion angle is 30 degrees, 45degrees, 60 degrees, 80 degrees or smaller, intermediate or largerangles to the tube axis. Optionally, the material is extruded with abend radius of 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 10 mm or intermediate,smaller or larger radii.

The radial arrangement of the extrusion apertures can be of variousdesigns. In one example, for example to ensure even filling of space308, three, four or more axial rows of apertures are provided. Each rowcan have, for example, one, two, three or more apertures. In anotherexample, apertures are provided only on opposing sides, so that, forexample, a user can select if to extrude towards cortical plates 302and/or 304, or not.

Rather than rows, a staggered arrangement may be used. One possibleadvantage for a staggered arrangement is that the delivery tube may beoverly weakened by aligned rows of apertures.

FIG. 5A shows a design of a delivery tip 500 in which round apertures502 in a staggered row design are used. FIG. 5B shows a design of adelivery tip 510 in which elongated rectangular apertures 512 arearranged in a non-staggered manner.

As shown, the shape of the apertures can be various, for example, round,ellipsoid, rectangular, axially symmetric or asymmetric, parallel to thetube axis or not and/or elongate. Optionally, the edges of the aperturesare jagged. Optionally, the shape of the apertures is selected for oneor more of the following reasons: shape of extrusion, preventing failureof the aperture and/or preventing failure of the delivery tip.Optionally, the apertures have a lip (optionally pointing inwards),which may assist in shaping the extrusion. For example, the lip may bebetween 0.1 and 1 mm in width, for example, 0.3 mm or 0.5 mm.

In an exemplary embodiment of the invention, the delivery tube is rigid.Optionally, the delivery tube is flexible or is mechanically shaped(e.g., using a vise) before insertion. In an exemplary embodiment of theinvention, the cannula is flexible and allows the insertion of adelivery tube which is curved at its end.

In an exemplary embodiment of the invention, the type of delivery tipused is selected by a user. Optionally, the delivery tip is replaceable,for example attached by a threading to the delivery system.

Optionally, an overtube or ring is selectively provided over part of thedelivery system to selectively block one or more of the apertures.

Referring briefly to FIG. 7A, a delivery tip 702 is shown, in which aguiding incline 706 is provided to guide the ejected material out of anaperture 704. Optionally, the use of such an incline reduces turbulencein the flow/distortion of the material and/or may assist in reducingfriction and/or improving control over the shape of the extrusion. Alsoto be noted is that material extrusion is provided on only one side ofthe delivery system. This may allow better control over the forcevectors inside the vertebra, caused by the extrusion. In an exemplaryembodiment of the invention, the angles defined by the guiding incline(90 degrees and in the plane of the tube axis) help determine theextrusion direction.

Also shown in FIG. 7A is a non-twisting pusher 708, which may reduceturbulence, friction and/or other difficulties in extruding thematerial, such as voids.

FIG. 5C shows a delivery tip 520, from which a material 526 is extrudedby a pusher 528 in a curved extrusion shape 522. In an exemplaryembodiment of the invention, the curvature is controlled by controllingthe relative friction on a proximal side 532 and on a distal side 530 ofan aperture 524. Alternatively or additionally, the degree of curvaturedepends on the size of the aperture and the shape of the incline.Optionally, the material is plastically deformed by the extrusion andmay maintain a shape conferred thereby barring contact with a deformingsurface (e.g., a bone plate).

Alternatively or additionally, extrusion 522 can be curved or bent dueto axial or rotational motion of tip 520. Optionally, the rotation isused to more uniformly fill space 308.

In an exemplary embodiment of the invention, the delivery tube movesand/or rotates during delivery. Optionally, a gear mechanism couplesmovement of the pusher with rotation and/or axial motion of the tube.Optionally, a manual motion is provided by an operator. Optionally, avibrator is coupled to the delivery system.

One consideration mentioned above, is that the amount of material inbarrel 408 may not be sufficient for a complete procedure. A matchingdesign is illustrated in FIG. 6A, in which the diameter of an innerlumen 602 of barrel 408 is the same as the diameter of an inner lumen604 of delivery tube 402. A longer delivery tube/barrel maybe requiredto reduce the number of barrel changes.

FIG. 6B shows an alternative design, in which a barrel 408′ has a lumen606 with a greater inner diameter and thus a greater storage volume.Optionally, the greater diameter provides an additional hydraulicamplification factor as the diameter changes. Optionally, a suddenchange in diameter may cause turbulence, resistance and/or voidcreation. In some materials, diameter change requires compression of thematerial. Optionally, as shown, a gradual change in diameter isprovided, with an intermediate sloped section 608 with an inner diametervarying between the diameters of lumen 606 and 604. Optionally, thepusher has a diameter matching lumen 606 and does not fit into lumen604. Optionally, an extension is provided to the pusher, which extensiondoes fit in lumen 604.

Referring to FIG. 6C, a gradually changing lumen 610 is provided in abarrel 408″. Optionally, the distal end of the pusher is made of aflexible material, which can conform to the change in diameter.Optionally, the flexible material is harder than the injected material.Alternatively or additionally, the distal end of the pusher is shaped tomatch the geometry of lumen 610.

In an exemplary embodiment of the invention, the lumen of the barrel islarger than the diameter of the pusher, at least in a proximal sectionof the barrel. After the pusher advances an amount of material into thebone, the pusher is retracted and the material remaining in the barrelis rearranged so that the next advance of the pusher will advance it.Optionally, the rearranging is by advancing a second plunger having adiameter similar to that of the barrel. Optionally, this plunger iscoaxial with the pusher.

The delivery tube may have various cross-sectional shapes, for example,circular, rectangular, arcuate and/or square. Optionally, thecross-section is matched to the shape of extrusion apertures.Optionally, the inside of the apertures is made sharp to cut theextruded material as it is advanced, instead of or in addition toplastically deforming or shearing it.

Exemplary Viscosity/Plasticity and Pressure

In an exemplary embodiment of the invention, the provided material has aviscosity of above 600 Pascal-second. Optionally, the material isadvanced into the body using a pressure of at least 40 atmospheres orhigher, for example, 100 or 200 atmospheres or more. If the material isplastic, it may have a hardness, for example, of between 10A shore and100A shore.

In an exemplary embodiment of the invention, pressure requirements arerelaxed at a beginning of a procedure, for example, if a void is createdby bone access or by rotation of the delivery system.

In an exemplary embodiment of the invention, the outer diameter of thedelivery system is, for example, 2 mm, 3 mm, 4 mm, 5 mm or intermediateor smaller or larger diameters. Optionally, the wall thickness of thedelivery system is 0.2 or 0.3 mm. Optionally, the wall thicknessincreases towards the distal tip.

It should be noted that the pressure used for delivery may depend on oneor more of: the friction between the material and the delivery system,the length of material being pushed, the pressure applied to thematerial, the pressure desired to be applied by the material to thevertebra, the manner in which the extrusion applies pressure against thevertebra, the viscosity of the material and/or other causes ofresistance to motion of the material.

Lower pressures may be used, for example, if it is deemed that thevertebra may be damaged or material leakage possible.

The volume injected may be, for example, 2-4 cc for a typical vertebraand as high as 8-12 cc or higher. Other volumes may be appropriate,depending for example, on the volume of space 308 and the desired effectof the injection.

In an exemplary embodiment of the invention, the rate of injection is0.25 cc/sec. Higher or lower rates may be provided, for example, between25 cc/sec and 0.1 cc/sec or less, and between 25 cc/sec and 1 cc/sec ormore. Optionally, the rate is controlled using electronic or mechanicalcircuitry. Optionally, the rate is decided by an operator responsive toexpected or imaged bone deformation in response to the pressure.Optionally, the rate is changed over the length of the procedure, forexample, being higher at a beginning and lower at an end. Optionally,the rate of injection is controlled by the operator (or automatically)responsive to a feedback mechanism, such as fluoroscopy.

Hydraulic Material Provision System

FIG. 7A shows a delivery system 700 which is powered hydraulically. Adelivery tube 710 is filled with material to be ejected into the body.Tube 710 is optionally detachable via a connection 712 to a body 714.Optionally, the connection is by threading. Alternatively, a fastconnection method, such as a snap connection, is used.

Body 714 converts hydraulic pressure provided via an input port 716 intoan advance of a pusher rod 708. Optionally, body 714 is integral withtube 710, but this prevents replacing tube 710 when the material to beejected is exhausted.

In an exemplary embodiment of the invention, incoming hydraulic (orpneumatic) fluid pushes against a piston 718, which advances pusher 708directly. Optionally, a hydraulic advantage is provided by the ratios ofthe piston and the pusher. Optionally, a spring 720 is provided forretracting pusher 708 when the fluid pressure is released.

Optionally, one or more spacers 722 are provided surrounding pusher 708,to prevent buckling thereof. Optionally, the spacers are mounted onspring 720. Optionally, spacers are provided at several axial locations.Alternatively to spacers, fins may extend from pusher 708 to body 714.

Optionally, in use, when material is used up, pressure is reduced,pusher 708 retracts and delivery tube 710 is replaced. Optionally, abarrel filled with material for injection, separate from tube 710 isprovided, so that tip 702 does not need to be removed from the body.

FIGS. 7B and 7C show two alternative methods of providing hydraulicpower. In FIG. 7B, a foot pedal pump 740 is used, in which a user placeshis foot on a pedal 744 and depresses it against a plate 742. Variousfoot pumps are known in the art. Optionally, a long press releases thepressure. Optionally, the hydraulic subsystem is a sealed system whichis provided ready to use (e.g., including fluid) to the user and/ordistributor. Exemplary lengths of the flexible tubing are between 0.2and 3 meters, for example, between 1 and 2 meters. However, greaterlengths can be used as well.

Also shown in FIG. 7B is a variant of body 714, indicated as 714′.Instead of a single spring 720, two springs 720′ are shown, with thespacer(s) between the springs. Optionally, the use of multiple springshelps maintain the spacers near a middle (or other relative length unit)of the pusher in danger of buckling.

FIG. 7C shows an alternative embodiment, in which a hand pump 760 isused, which pump can be of any type known in the art, for example, amechanism 762 comprising a piston 764 and a cylinder 766. Optionally,the pumping is by rotating piston 764 elative to cylinder 766, whichcomponents include matching threading. Alternatively, linear motion isused. Optionally, a hydraulic gain is achieved between the pump and thedelivery mechanism, for example a gain of 1:3, 1:5, 1:10 or any smaller,intermediate or greater gain.

In an exemplary embodiment of the invention, the hydraulic system isprovided as a disposable unit, with a non-disposable (or a disposable)foot pump.

FIG. 7D shows a disposable mixing and storage chamber 770 and FIG. 7Eshows a reusable pump 750 with a disposable hydraulic capsule 754.

Referring to FIG. 7D, a same capsule 770 is optionally used both formixing and for storage/delivery of a material. Optionally, the materialis a setting cement such as PMMA. In the embodiment of a hydraulicdelivery stream, a flexible tube 772 is optionally permanently connectedto a pump (FIG. 7E). When fluid is provided through tube 772, a piston774 moves through a cylinder volume 776 and pushes the material out(e.g., and into a delivery system). In the figure, the capsule is shownloaded with a mixer 778. Optionally, materials are provided into volume776 using a detachable funnel (not shown) and then the funnel is removedand mixer 778 inserted instead. In the exemplary mixer shown, a cap 782covers cylinder 776. When mixing is completed, this cap may be replacedby a fitting adapted to couple to the delivery tube.

In use, a handle 780 is rotated, rotating a shaft 786 having a rotor 788defined thereof, for example, as a helix. An optional stator 789 isprovided. An optional vent 784 may be connected to a vacuum source, tosuck out toxic and/or bad smelling fumes caused by the setting of thematerial. Optionally, a viscosity of the materials is estimated by thedifficulty in turning the handle. Optionally, the handle includes aclutch (not shown) that skips when a desired viscosity is reached.Optionally, the clutch is settable. Optionally, a viscosity meter isused or viscosity is estimated based on temperature, formulation andtime from mixing.

Cap 782 optionally includes a squeegee or other wiper, to wipe materialoff of mixer 778 when it is removed from capsule 770.

Referring to FIG. 7E, tube 772 connects to a capsule 754 which includesa piston 798 and a volume 797, pre-filled with fluid. In an exemplaryembodiment of the invention, a frame 756 is provided attached to pump750 for selectively receiving capsule 754.

Pump 750 is, for example, a hydraulic oil based pump-mechanism 752 thatextends a pushing rod 795 which advances piston 798.

In the embodiment shown, a foot pedal 758, attached to an axis 791,forces a piston 755 into a cylinder 792. A one way valve 794 allows thefluid in cylinder 792 to flow into a volume 749 where it pushes againsta piston 757. When pedal 758 is released, a spring (not shown) pulls itback to an upward position and allows a hydraulic fluid to flow from astorage chamber 759 (e.g., which surrounds the pump) through a one wayvalve 793 into cylinder 792.

A pressure relief valve 751 is optionally provided to prevent overpressurizing of cylinder 749. In an exemplary embodiment of theinvention, a spring 796 is provided to push back piston 757 and pusher795 with it, when pressure is released. Optionally, pressure is releasedusing a bypass valve 753, which is manually operated. Once pusher rod795 is retracted, capsule 740 is optionally removed.

Unit Material Provision System

FIG. 8A shows a delivery system 800 in which material is provided asdiscrete units, each of which is of relatively small volume, forexample, ½, ¼, 1/7, 1/0 or less of the amount required for treatment.One potential advantage of working in units is that an operator is moreaware of the effect of his/her actions as each action can only injectone unit. Another potential advantage of working in units is that unitswith different material properties may be provided during a procedure.Another potential advantage is that units being small will generallyexhibit a smaller friction with the delivery system.

System 800 comprises a delivery tube 802 having one or more extrusionapertures 804 at its tip. A barrel 808 on which tube 802 is mounted,also includes an optional magazine 820, described below. A body 818 withan optional nut threading is optionally attached to barrel 808. A pusher810 lies within delivery tube 802 and/or barrel 808.

In an exemplary embodiment of the invention, a handle 812 is providedwhich includes a battery powered mechanism for advancing pusher 810. Ahydraulic mechanism such as described above may be used instead.Optionally, one or more switches are provided, for example, an on/offswitch 816 and a direction switch 814. Optionally, when pusher 810completes its forward motion, it is automatically retracted. Optionally,only a single switch is needed, activation of which causes extrusion ofone unit. In an exemplary embodiment of the invention, handle 812 isrotationally locked to body 818, for example using one or more guidepins.

In an exemplary embodiment of the invention, handle 812 comprises amotor and a battery that rotate pusher 810. An alternative mechanism isdescribed below.

Referring to magazine 820, in an exemplary embodiment of the invention,the magazine comprises discrete units 822 of material (a unit 824 isshown inside tube 802). Optionally, a spring 826 is used to push theunits towards tube 802. Optionally, the magazine is filled with acontiguous mass of material and the units are defined by the cuttingaction caused by pusher 810 pushing a unit of material away from themagazine.

In an exemplary embodiment of the invention, a magazine is preparedahead of time, for example, by a manufacturer, who fills the magazinewith a non-setting material.

In an exemplary embodiment of the invention, the magazine is loaded witha series of units of different properties, for example, responsive to anexpected progress of a procedure, for example, first providing a softmaterial and then providing a harder material, or vice versa.Alternatively, a rotating magazine is used, in which a user can selectwhich of several compartments will load barrel 808 next. This allowsfine control over the injected material. In an exemplary embodiment ofthe invention, an operator can remove magazine 820 at any time andreplace it with a different magazine. Optionally, this is done whilepusher 810 is forward, so that there is no danger of backflow from thebody.

Optionally, one or more of the units comprises or is an implant device(rather than an amorphous and/or homogenous mass), for example, anexpanding implant or an implant whose geometry does not change.Optionally, one or more of the units comprises a cross-linked material.

In an exemplary embodiment of the invention, the delivery system usedcomprises two or more delivery tubes (optionally the combined geometryhas a cross-section of a circle or of a figure eight). Optionally, eachtube has a separate pusher mechanism and/or a separate material source(e.g., a magazine). Optionally, the two tubes are used simultaneously.Optionally, an operator can selectively use one tube. Optionally, thematerials provided in each tube are components that react chemically onewith another. Optionally, electronic control is provided to control therelative provision rates of the two tubes. Optionally, this allowscontrol over the final material properties. Optionally, the use of twoor more tubes allows a layered structure to be built up in the body.Optionally, one of the tubes delivers a setting material and the othertube delivers a non-setting material. In an alternative embodiment, eachtube is used to provide a different component of a two componentmaterial. Optionally, the two tubes meet at their distal end, to ensuremixing of the components.

In an exemplary embodiment of the invention, the delivered material isCORTOSS by Orthovita inc. (US), a composite of Bis-GMA, Bis-EMA andTEGDMA. This material is optionally mixed along the path in the deliverytube.

In an exemplary embodiment of the invention, instead of the units beingprovided by a magazine or by a cutting mechanism, a partial unitbehavior is provided by the motor of handle 812 stopping after every“unit” advance. Optionally, mechanical stops are provided for ahydraulic mechanism, if used. Optionally, instead of stopping, a soundis provided when a unit is injected or based on a different logic, forexample, when 50% or another percentage of planned amount of material isprovided. Optionally, a CPU is provided which analyzes an image providedby an imaging system and generates a signal when a sufficient and/ornear sufficient and/or over-load amount of material is provided. Othercircuitry may be used as well.

Optionally, circuitry is provided for controlling the rate and/orpressure of material provision. Optionally, the circuitry stopsadvancing if a sudden change in resistance is perceived.

In an exemplary embodiment of the invention, the delivery systemincludes pre-heating or pre-cooling of the injected material and/or oftube 802. In an exemplary embodiment of the invention, a Peltier coolerand/or a resistance heater are provided in barrel 808. Other cooling orheating methods, such as based on chemical reactions or phase changingmaterials, may be used.

In an exemplary embodiment of the invention, the magazine is a longcoiled magazine. Alternatively or additionally, the deformable materialis folded in the magazine. Optionally, the magazine is elongated.Optionally, separate loading and pushing mechanism are provided. In anexemplary embodiment of the invention, for loading, a unit is insertedthrough a slot in the side of the barrel. For pushing, the unit isadvanced under a low pressure past the slot (or the slot is sealed) andonly then is significant pressure required to advance the unit, forexample, once the leading edge of the unit reaches the extrusionapertures.

FIG. 8B shows the implementation of a unit delivery method even withouta cassette. A delivery tip 840 is shown with an aperture 842 throughwhich multiple units 822 are shown exiting. Optionally, an indication isprovided to the user as a unit exits, for example, based on motion of apusher used. Optionally, the system of FIG. 8A is used to load a seriesof units 822 into the barrel, for example, pulling back the pusher aftereach unit is advanced past the cassette.

Battery Powered Pusher

FIGS. 9A and 9B show a material pusher 900 with reduced materialtwisting, in accordance with an exemplary embodiment of the invention.

As in the delivery systems described above, pusher 900 comprises adelivery tube 902 having one or more apertures 904 near its end.Optionally, an offset is provided between the apertures and the far tipof tube 902, for example, to ensure centering (or other positioning) ofthe extruded material, for example preventing the material from beingprovided too close to a far end of the vertebra, if the delivery systemis pushed forward.

Tube 902 is mounted (e.g., optionally replaceably) to a body 908. Apusher 910 is used to advance material through tube 902.

In an exemplary embodiment of the invention, in use, an operator pressesa switch 912, for example, to select between forward, backwards and nomotion of pusher 910. Power from a battery 914 (or a hydraulic or othersource) is conveyed to a motor 916. Rotation of the motor causes a nut922 to rotate relative to pusher 910. Optionally, a series of gears areused which may or may not provide a mechanical advantage, depending onthe implementation. In an exemplary embodiment of the invention, motor916 rotates a gear 918 that rotates a gear 920, which rotates nut 922which is coaxial thereto. Optionally, a rotation preventing element 924,for example, a rectangular element 924 is mounted on pusher 910 andprevents rotation thereof.

Optionally, one or more sensors are used to detect the extremes ofpositions of pusher 910, when it is advanced and when it is retracted.In the example shown, a micro-switch 926 and a micro-switch 928 detectthe ends of motion of pusher 910, for example, using a bump orelectrically conducting section 930 (depending on the sensor type used).Alternatively or additionally, a positional encoder is used, forexample, by counting rotation, or a separate encoder as known in the artof encoders.

FIG. 9B shows system 900 after extrusion is effected, showing extrusions932. Optionally, extrusions 932 are an extension to tube 902, prior tothem being cut off by pusher 910. In an exemplary embodiment of theinvention, rotation of tube 902 causes extrusions 932 to act as areamer. In an exemplary embodiment of the invention, the viscosity andshear strength of the material are selected to effect a desiredlimitation on the reaming abilities, for example, to prevent damage tobone.

Optionally, one or more gears are provided to rotate and/or oscillatethe delivery tube as the material is advanced. Optionally, periodic orramp axial motion is provided, by motor means. Optionally, the distaltip of the delivery tube is made soft, for example by attaching a softtip thereto, to reduce or prevent damage to the vertebra.

Sleeve Provision System

FIGS. 10A and 10B shows a sleeve based delivery system 1000, inaccordance with an exemplary embodiment of the invention. FIG. 10A is ageneral cut-open view of system 1000, in which a sleeve 1010 is notshown. FIG. 10B shows the distal portion of system 1000, includingsleeve 1010 mounted thereon.

The embodiment of FIGS. 10A-10B also illustrates a refilling mechanismby which the delivery tube includes a port to which a refill system canbe connected to refill the delivery tube with material to be injectedinto the body.

A pusher 1004 pushes material that is found inside a delivery tube 1002.In the embodiment shown, the material is ejected past a tip 1008 ofdelivery tube 1002. A sleeve 1010 is provided so that the sleeve liesbetween the material and delivery tube 1002. An optional tube cutter1012, such as a knife is shown to optionally split the tube after itexits the body. A pulley system 1011 for collecting the split tube isalso shown.

In operation, an amount of material is either provided in tube 1002 oris injected into it, for example, via a port 1016 in pusher 1004.Advancing of pusher 1004, for example, by applying force to a knob 1018attached thereto, for example manually, using a motor or using othermechanisms described herein, pushes against the material in tube 1002.At the same time, sleeve 1010, which is attached to pusher 1004, forexample, by a crimping 1014, is pulled along with the material. Portionsof sleeve 1010 reaching distal tip 1008 of tube 1002, fold back towardsa body 1006 of delivery system 1000. When sleeve 1010 reaches knife1012, it is optionally split so that it can pass over tube 1002 andpusher 1004. A thread or wire or other coupling 1013 is attached to theproximal (split) side of sleeve 1010 (e.g., via a connector 1019) andvia a pulley 1011 is pulled as pusher 1004 advances. A slide 1020 isoptionally provided to guide the motion of the split sleeve.

It should be appreciated that such a sleeve system can also be used fordelivering implants rather than material. In one example, a compressedplastic implant, for example, polyurethane, which is compressed radially(and extended axially) is advanced using a sleeve system, to reducefriction. Optionally, the sleeve material is selected according to thematerial being used and/or the tube material. In another example, thesleeve system is used to deliver a self-expanding implant, for example,as described in WO 00/44319 or in WO 2004/110300, the disclosures ofwhich are incorporated herein by reference.

It is noted that a sleeve system may also be flexible. Optionally, thesleeve is formed of a chain-link or a knitted material, rather than anextruded plastic polymer tube. Optionally, the sleeve is formed ofmultiple layers of materials, for example by extrusion or by lamination.Optionally, fibers or other strengthening means are provided to reduceelongation. Optionally, the sleeve is formed of a material thatwithstands heat and/or chemical byproducts caused by PMMA. Optionally,the sleeve is preformed to elastically expand when it exits the deliverytube. Optionally, the sleeve is perforated or includes a plurality ofapertures therein.

Optionally, the sleeve elutes one or more treatment materials.Optionally, the sleeve elutes one or more catalysts or catalysisretarding materials, for example, to prevent or slow-down reactions inthe delivery system and/or speed them up out of the delivery system.

Optionally, a layer of oil or other lubricant is provided in addition toor instead of the sleeve.

Optionally, the sleeve remains inside the body, for example, beingformed of a bio-degrading materials or maintaining its form. Optionally,when degrading, strengthening fibers or other elements remain to enhancethe strength of the extruded material or implant.

FIG. 10C is a cross-sectional view of a variant system 1000′ in which apusher 1004′ is flexible enough to bend. This allows a body 1006′ of thedevice to be manufactured in a non-linear shape, for example, in theshape of revolver, which may be easier to hold. Optionally, one or morewheels, bearings or slides (not shown) are used to guide pusher 1004′.Optionally, pusher 1004′ can be made more flexible as some of the motiveforce used to move the material is provided by the sleeve pulling thematerial forward. Alternatively or additionally, some reduction issupported by the reduced friction.

Optionally, a sleeve system is used with a magazine system, for example,the units being provided through port 1016.

Optionally, the sleeve is pre-split and includes an overlap to preventfriction in the delivery tube. Optionally, this allows a magazine toload the sleeve from the side.

FIG. 10D shows a further, compact, variant 1000″ in which a pusher 1004″is made flexible enough to fold over itself, so body 1006″ can be ofsmaller dimensions. It should be noted that these more compact and/ornon-linear embodiments can also be practiced without the sleeve feature.The sleeve pullback mechanism is not shown here.

FIG. 10E shows a variant system 1000″′ in which a pusher 1004″′ isreduced in size axially. In this design the motive force is provided bypulling back the cut sleeve 1010 using a knob 1040 (or a motorized ormechanical gain or other means). This pulling back advances a shortenedpusher 1004″′. Optionally, pusher 1004″′ is provided as a sealed end ofsleeve 1010. A body 1006″′ of the system can be very compact, dependingon the method of pulling back on knob 1040. Op two or more symmetricallypositioned knifes 1012 are provided, to allow for proper mechanicalsupport of tube 1002 by body 1006″′. Optionally, the tube is precut.

In an exemplary embodiment of the invention, it is noted that pusher1004 is separated from the injected material by the sleeve. Optionally,a hydraulic system is used to advance the pusher, for example (in FIG.10F) attaching a flexible tube to pusher 1004″′ in tube 1002.

In an exemplary embodiment of the invention, sleeve 1010 is used toisolate the body itself from the hydraulic system, possibly allowing fora system with a higher probability of leaking.

In the embodiments shown, the material exited from the distal end 1008of tube 1002. Optionally, a stop is provided at the end, so that thematerial is forced sideways. Optionally, the stop is not attached totube 1002 at end 1008 thereof. Rather a thread, running through tube1002 and/or outside thereof (or more than one thread) attaches the stopto the body of device 1000. Optionally, the thread runs through a narrowlumen formed in pusher 1004.

Alternatively, one or more elements which attach the stop to tube 1002,serve to split sleeve 1010, at tip 1008 of tube 1002. In an exemplaryembodiment of the invention, the stop is attached to tube 1002 after thesleeve is mounted thereon. Alternatively, the sleeve is pre-split,pulled through tube 1002, past the elements and attached to connector1019.

In an alternative embodiment of the invention, the sleeve is providedtotally within the delivery tube. In one embodiment (not shown), thedelivery tube comprises two coaxial tubes and the inner tube serves asshown by tube 1002 in FIGS. 10A-10E.

In another embodiment, the fact that the delivery tube is full ofmaterial is taken advantage of, in that the material (316) serves toprevent the tube from collapsing when it is simultaneously pushed fromone end and pulled from the other. This may depend on the viscosity ofthe material and/or on the shape of the distal tip of the deliverysystem. Optionally, the distal end is slightly flared to define afolding over location for the sleeve.

FIG. 10F shows such an embodiment, of a delivery system 1050, in whichsleeve 1010 is provided within delivery tube 1002. As can be seen afolding over location 1052 for the sleeve is provided past the end oftube 1002. In an exemplary embodiment of the invention, a ring (notshown) is provided past the end of tube 1002 and around which the sleeveis folded. This ring serves as a scaffold for the folding, but due toits having a diameter greater than an inner diameter of tube 1002 (or atleast being misaligned if the ring and/or tube are not circular incross-section), cannot be pulled into the tube by retraction of sleeve1010.

In an alternative embodiment of the invention, sleeve 1010 does not foldback towards system 1000. Rather, the sleeve is pushed into the vertebrawith the material. Optionally, once out of the confines of tube 1002,the material can tear the tube. In an alternative embodiment, the sleeveremains intact and encloses the material, sausage-like, in the body. Thesleeve may be formed of biocompatible, bioabsorbable and/or implantgrade material.

Squeeze Based Material Provision

In an exemplary embodiment of the invention, the material is squeezedout of the delivery system rather than pushed. FIG. 11A shows a squeezebased system 1100, in which a delivery tube 1102 is made out of asqueezable material, such as a polymer or annealed metal. A pair ofrollers 1104 (or one roller and an opposing anvil, not shown) advancetowards the distal side of tube 1102, squeezing it flat and forcingmaterial that fills the tube to migrate distally. Various motionmechanism can be used. In the figure, the motion mechanism is a lineargear 1108 which engages a gear 1106 that is coaxial with roller 1104.When the roller is rotated, the linear gear advances the roller. Variouspower sources may be used, for example, electric motors and hydraulicpower. Also, other power trains may be used. The rollers are optionallymade of stainless steel.

FIG. 11B shows a delivery system 1120, in which a squeeze element 1124slides rather than rolls against a delivery tube 1122. Tube 1122 isoptionally rolled around a pin 1134. Various mechanisms can be used tomove squeeze element 1124, for example a motor 1130 attached to a cable1126 via an optional pulley 1128.

Tamping Method

In an exemplary embodiment of the invention, friction is reduced byreducing the length of motion of the material inside a delivery tube. Inone method, a small amount of material is provided into a distal side ofa delivery tube (while outside the body). Then the distal part isinserted into the body and a tamping tool is provided into the proximalpart.

This process may be repeated several times until a desired amount ofmaterial is provided into the body.

Penetrating Delivery System

In some embodiment of the invention, the delivery system also penetratesto the bone and/or penetrates the bone. Optionally, this obviates theneed for a separate cannula and/or may simplify the procedure.Optionally, the delivery tube is kept in the body when it is beingrefilled with material to be injected.

FIG. 12A shows a penetrating delivery system 1200. A distal tip 1202 isformed in a manner suitable for drilling in bone. This is shown ingreater detail in FIGS. 12B and 12D.

A hydraulic pump or mechanical ratchet advance mechanism is optionallyused, with a handle 1206 used for pumping shown.

A potential advantage of a one piece system is that fewer parts areneeded. If the system is preloaded with all the material needed, forexample, at a manufacture, no equipment changes are needed. Optionally,the use of a side aperture 1204 allows the tip to be a drilling tip.Optionally, the use of smaller diameter tubes allows fewer parts to beused, as drilling is simplified.

Optionally, the proximal end of system 1200 is adapted for tapping witha mallet.

FIG. 12C shows an alternative embodiment of a system, 1230, in which thesystem is adapted to ride on a guidewire 1236, for example, a K-wire. Inan exemplary embodiment of the invention, a bore 1238 is formed in adrilling section 1232 of system 1230. Alternatively, the bore is to theside of the drilling head, for example, exiting through an aperture 1234which may also be used for extruding material. Optionally, the pusher(not shown) is drilled as well. Optionally, the diameters of the drilledholes are too small for the material to exit through. Alternatively,bore 1238 is used for extruding material, after the K-wire is removed.

In an exemplary embodiment of the invention, the material is predrilledwith a bore, to allow passage of the guidewire therethrough. Optionally,this bore is provided with a sleeve. It is noted that absent axialpressure on the material, the material will generally not flow into thedrilled bore. Alternatively or additionally, the guidewire is coatedwith a suitable friction reducing coating, solid or fluid.

Optionally, the delivery tube is loaded after the delivery tube isguided into the body (and the guidewire removed), for example using abarrel storage means or a unit magazine as described above.

Optionally, a separate lumen is defined for a K-wire. Optionally, thatlumen is a collapsible lumen. However, until pressure is applied to thematerial to be delivered, it remains un-collapsed. Once the guidewirecompleted its task, it is removed and pressure applied to the material,collapsing the guidewire channel and improving the flow characteristics(by increasing effective inner diameter of the delivery tube.

In an exemplary embodiment of the invention, a cannula is not needed,for example, if the delivery system rides on the guidewire or if thedelivery system is used to directly penetrate the bone. Optionally, thedelivery tube of the delivery system is not removed once inserted intoor to the bone, for example, using a barrel or pumping mechanism asdescribed above to reload the delivery mechanism if required. Once thesystem is reloaded, the pusher can advance the material into thedelivery tube where it can then be advanced into the bone.

Optional Additional Therapy

In an exemplary embodiment of the invention, the provision of materialis enhanced by additional therapy. Optionally, the additional therapycomprises thermal therapy. Optionally, the material is pre-heated orpre-cooled. Optionally, the pre-heating or pre-cooling also serves apurpose of controlling the material properties and/or setting behavior.

In an exemplary embodiment of the invention, the heating is by contactheat (conduction) or by light, for example a flash lamp or a lasersource. Alternatively or additionally, the delivery system radiatesheat. Optionally, a microwave or other wireless heating method is used.

Optionally, heating is provided separately from material provision. Inone example, a heated guidewire is provided into the vertebra.Optionally, the guidewire extends one or more protrusions, to guidethermal energy into the nearby tissue. Optionally, a thermal sensor isprovided to control the temperature in the vertebra and/or prevent overheating.

Exemplary Materials

Various materials are suitable for use with exemplary embodiments of theinvention. Some of the materials which can be used in some embodimentsof the invention are known materials, for example, PMMA, however, theymay be used at unusual conditions, for example at a semi-hardenedcondition. Also, while putty materials may be known, they are nottypically used for injection through a small bore into bone.

It should be noted that while specific examples are described it isoften the case that the material composition will be varied to achieveparticular desired mechanical properties. For example, differentdiagnoses may suggest different material viscosities.

In an exemplary embodiment of the invention, for non-hardeningmaterials, the material can be allowed to set outside the body. Aftersuch setting the material may be washed or ventilated. In this manner,some materials with potentially hazardous by-products can be safelymixed and then used in the body. Optionally, a material is tested tomake sure toxic byproducts are removed to below a safety threshold.Optionally, a testing kit is provided with the delivery system.

In an exemplary embodiment of the invention, the material is selected sothat its mechanical properties match the bone in which it will beimplanted. In an exemplary embodiment of the invention, the material ismatched to healthy or to osteoporostic trabecular bone. Optionally, themechanical properties of the bone are measured during access, forexample, based on a resistance to advance or using sensors providedthrough the cannula or by taking samples, or based on x-raydensitometers measurements.

In general, PMMA is stronger and has a higher modulus than trabecularbone. For example, Trabecular bone can have a strength of between 3-20megapascal and a Young modulous of 100-500 megapascal. Cortical bone,for example, has strength values of 170-190 gigapascal and Young modulusof 13-40 gigapascal. PMMA typically has values about half of Corticalbone.

In an exemplary embodiment of the invention, the material is selected tobe less than 120% as strong and/or young modulus as the expected bone tobe treated. Optionally, the values of one or both of strength and youngmodulus are 10%, 20%, 30%, 40% or less reduced from that of trabecularbone. It should be noted that if less of the vertebra is filled, theinjected material will be supported, at least in part, by trabecularrather than cortical bone, depending for example on the method of filingof interior 308.

Exemplary Non-Hardening Material

In an exemplary embodiment of the invention, the material used is aputty like material. One example of a putty-like material is ahydroxyapatite with an increased ratio of sodium alginate. For example,the increased ratio can be 8% or 10%. While this material does harden inthe body, it does not set to a hardened condition absent humidity. Thusit can be prepared ahead of time and pre-stored in a delivery system,for example by a manufacturer. In an exemplary embodiment of theinvention, the added material slows down water absorption so that whilesufficient water enters the material to initiate setting, not enoughenters to cause dissolution. An example of this material is described inIshikawa et al., “Non-decay fast setting Calcium phosphate cement:Hydroxyapatite putty containing an increased amount of sodium alginate”,J Biomed Mater Res 36 1997, 393-399, the disclosure of which isincorporated herein by reference. More details may be found in “Effectsof neutral sodium hydrogen phosphate on setting reaction and mechanicalstrength of hydroxyapatite putty”, by Kunio Ishikawa, Youji Miyamoto,Masaaki Takechi, Yoshiya Ueyama, Kazuomi Suzuki, Masaru Nagayama andTomohiro Matsumura, in J Biomed Mater Res, 44, 322-329, 1999, thedisclosure of which is incorporated herein by reference.

Other calcium derivative cements, bone chips and/or fillers may be usedas well. Bone chips, depending on processing may have a limited shelflife. Some of these materials generally harden (or combine with bonegrowth) after a relatively long time, such as more than a week, morethan a month or more than 3 months.

Additional Exemplary Non-Hardening Material

In an exemplary embodiment of the invention, the material used is amixture of LMA (lauryl methacrylate) and MMA (methyl methacrylate).Depending on the ratio used, different mechanical properties andviscosities can be achieved. FIG. 13 is a graph showing the relativeviscosities of PMMA and various ratios of the copolymer material. In theexample shown, as the ratio of LCA decreases, viscosity goes down.

Diblock copolymers of MMA and LMA were synthesized by anionicpolymerization using DPHLi as initiator in THF at −40° C. with thesequential addition of monomers. The molecular weight distribution ofthe polymers was narrow and without homopolymer contamination when LMAwas added to living PMMA chain ends.

In an exemplary embodiment of the invention, the ratio used are 80:20,70:30, 60:40, 50:50, 30:70, 20:80 or intermediate, smaller or largerratios (by volume).

Experiment: Materials and Methods

Starting Materials

Medicinal distillate methyl methacrylate and lauryl methacrylatestabilized with 10-100 ppm of the monomethyl ether of hydroquinone wereused as received from Fluka, Germany. Benzoyl peroxide (BPO) waspurchased from BDH Chemicals, England. N Barium sulfate (BS) wasobtained from Sigma-Aldrich (Israel). All solvents were analytical-gradefrom Biolab (Jerusalem, Israel) and were used as received.

Polymerization

Polymerization reactions were carried out in a single necked roundbottom flask equipped with a magnetic stirring. In a typical reaction,60 ml MMA (0.565 mol), 50 ml LMA (0.137 mol), 220 mg of Benzoyl Peroxide(0.9 mmol), and 100 ml THF were transferred. The amount of BPO wasadjusted to each of the compositions according to the total amount ofthe monomer's mols. The amount of the THF was equal to the total volumeof the monomers (table 1). The content was heated to a polymerizationtemperature of 70-75° C. for 20 hours, then the solution wasprecipitated in sufficient amount of methanol and left to mix for fourhours. Finally, the polymer was dried in an oven at 110° C. undervacuum.

TABLE 1 copolymers composition Copolymer MA LMA BPO THF (MA:LMA)(ml/mol) (ml/mol) (mg/mol) (ml) 100:0  100(0.94)  0(0)  285(1.18) 10080:20 80(0.75) 20(0.07) 258(1.06) 100 70:30 70(0.66) 30(0.10) 239(0.99)100 60:40 60(0.56) 40(0.14) 220(0.9)  100 50:50 50(0.47) 50(0.17)201(0.83) 100 40:60 40(0.38) 60(0.20) 182(0.75) 100 30:70 30(0.28)70(0.24) 163(0.67) 100 20:80 20(0.19) 80(0.27) 144(0.6)  100  0:1000(0)  100(0.34)  107(0.44) 100

The dried polymer was milled to a fine powder (Hsiangtai Sample mill,model sm-1, Taiwan) and mixed with barium sulfate (30% w/w). The mixturewas heated in a glass inside a sand bath to 140° C., until melting ofthe polymer. The mixture left to cool, and milled again. This procedurewas repeated at least three times, until a homogeneous off-white polymerwas received, which could be melted into loadable slugs for the deliverysystems and magazines described above.

Characterization

Molecular weight and polydispersity were analyzed by Gel permeationchromatography, GPC system consisting of a Waters 1515 isocratic HPLCpump with a Waters 2410 refractive-index detector and a Rheodyne(Coatati, Calif.) injection valve with a 20-μL loop (Waters Ma). Thesamples were eluted with CHCl₃ through a linear Ultrastyragel column(Waters; 500-Å pore size) at a flow rate of 1 mL/min.

¹H—NMR spectra were recorded on a Varian 300 MHz instrument using CDCl₃,as solvents. Values were recorded as ppm relative to internal standard(TMS).

A Cannon 1C A718 Ubbelhold viscometer was used for the viscositymeasurements of the polymer. The measurements were performed at 30° C.with toluene as a solvent.

Water Absorption Capacity

Swelling behavior of acrylic bone cements was carried out fromaccurately weighed films of 0.8 mm thickness. Films were introduced in0.9 wt % NaCl solution (20 ml) and kept at 37° C. The water sorptionkinetics in 20 ml saline solution were evaluated in two specimens ofeach bone cement (containing 30% barium sulphate).

Equilibrium gain was determined gravimetrically at different periods oftime. The uptake of water was recorded at 30 min intervals in thebeginning and spacing out these intervals until the equilibrium wasattained. At appropriate times, the samples were removed, blotted withabsorbent paper to remove the water attached on its surface and weighed.The percentage of Equilibrium gain was obtained from each specimen usingthe following expression:

${{Hydration}\mspace{14mu}{{degree}(\%)}} = {\frac{{{Weight}\mspace{14mu}{of}\mspace{14mu}{swollen}\mspace{14mu}{specimen}} - {{initial}\mspace{14mu}{weight}\mspace{14mu}{of}{\mspace{11mu}\;}{specimen}}}{{initial}\mspace{14mu}{weight}\mspace{14mu}{of}\mspace{14mu}{specimen}} \times 100}$Results:

100% PMMA: Average 1.845% (+0.045)

-   -   Initial weight (g) 0.2156 and 0.2211    -   Weight of specimen at equilibrium (g) 0.2195 and 0.2253    -   Equilibrium gain (%): 1.8 and 1.89;

60% PMMA, 40% PLMA: Average 1.65% (+0.235)

-   -   Initial weight (g): 0.1161 and 0.1402    -   Weight of specimen at equilibrium (g) 0.1183 and 0.1422    -   Equilibrium gain (%): 1.42 and 1.89;

50% PMMA, 50% PLMA: Average: 1.02% (+0.28)

-   -   Initial weight (g): 2700 and 0.2371    -   Weight of specimen at equilibrium (g) 0.2720 and 0.2400    -   Equilibrium gain (%): 0.74 and 1.3;        Compression Testing

These tests were conducted using an Instron 4301 universal testingmachine provided with a load cell of 5 kN, and at a cross-head speed of20 mm/min. A known weight of polymer was melted in a glass inside a sandbath. The bath was heated at 150° C. for two hours, and then bariumsulfate was added (30% w/w) and mixed well several times, untilhomogenous dough was received. Cylindrical specimens of 6 mm in diameterand 12 mm high were prepared by forcing the melted copolymers into theholes of a Teflon mold. One side of the mold was covered with Teflonplates and secured with clamps. The specimens were cooled for 20 minutesin the mold, then the upper side was cut to the mold shape, and thespecimens removed from the mold, finished to a perfect cylindricalshape. The test took place at least 1 week after aging in air at 23±1°C. For each cement composition, six specimens were tested.

The elastic modulus and the maximal strength force were obtained.

Results:

Molecular Weights and Viscosity Measurement

The number and weight average molecular weights of poly(La-MA),poly(MMA) and their copolymers were obtained from gel permeationchromatography. The polydispersity index varies in the range of 1.6 to2.87. The viscosities of the polymers are obtained using Toluene assolvent at 25° C. The intrinsic viscosities (η) were obtained byextrapolating η_(sp C) ⁻¹ to zero concentration. The molecular weightsand viscosities are presented in Table II.

TABLE II composition Feed Ratio GPC analysis of polymers MMA:LMA NMRAnalysis Poly- Vol.-% (mol-%) [MMA]:[LMA] M_(n) M_(w) dispersity [η]100:0 (100:0)  100:0  65190 119544 1.833 0.544   8:2 (91.5:8.5)[88]:[12] 69118 119194 1.724 0.421 7:3 (87:13) 87:13 63006 112442 1.780.393 6:4 (84:16) 84:16 73295 118384 1.615 0.366 1:1 (74:26) 69:31 94167135880 1.44 0.351 4:5 (69:31) 70:30 55455 104711 1.888 0.316 4:6 (64:36)62:38 75648 134745 1.781 0.305 3:7 (56:44) 56:44 35103 79986 2.27 0.2212:8 (40:60) 40:60 23876 68720 2.87 0.178 0:100 (0:100)   0:100 2735075146 2.74 0.083Compressive Test

The results of the compressive test are collected in Table III as afunction of compressive strength and modulus. The influence on themechanical behavior of adding lauryl methacrylate monomers can beclearly observed. The introduction of higher percentages produces adecrease that is more pronounced at 50% (v/v) LA. The compressivemodulus shows a drastic decrease as the content of LA increases. Thisdrop may be related to the structure modification of the matrix by theintroduction of LMA. This drop may also limit the use of somecompositions for some applications.

TABLE III compression test results Composition Max strength ModulusMA:LA (V %) (Mpa) (Mpa) 1:0 106.8(9)   2478(220)  8:2 82.5(17.1)1100.7(129)   7:3 63.3(13.2) 634.5(116)  6:4 48(11) 550(250) 5:518.9(4.5)  69.6(20)  4:6 1.9(0.2) 49.5(11.8) 3:7 19.19(3.42)  8.3(1.2)2:8 0.253(0.06)   1.71(0.417)Material Modifications

Optionally, various additives are added to the materials describedherein, to modify their properties. The adding can be before setting orafter setting, depending on the material. Exemplary materials that canbe added include fibers (e.g., carbon nanotubes or glass fibers) ofvarious lengths and thicknesses, aggregates and/or air bubbles.

In an exemplary embodiment of the invention, if the material ismanufactured to be anisotropic, it can be advanced into the body in adesired direction, for example, by selecting a delivery path (e.g.,storage, tube, aperture) to reduce twisting and/or deformation.Optionally, such materials are provided as short units (FIG. 8).

Softening and Semi-Hardening Materials

In an exemplary embodiment of the invention, the material used softensafter provision into the body. In an exemplary embodiment of theinvention, the material comprises an additive that disperses or weaknessin water or body fluids, for example, salt. A softening material may beuseful if the forces required for height restoration are smaller thanthe forces required for maintaining height. Softening times areoptionally controlled by mixing in a gel material which slows down waterpenetration into the extruded material.

Semi-Hardening Materials

In an exemplary embodiment of the invention, the material used sets tonon-hardened condition. In an exemplary embodiment of the invention, thematerial comprises MMA, LMA and NMP. NMP solvates in water, allowing thematerial to set somewhat. In an exemplary embodiment of the invention, ahardened condition is avoided, possibly preventing the induction offractures in nearby vertebra.

Use of Hardening Materials

In an exemplary embodiment of the invention, the above described devices(e.g., delivery) are used with a material which sets to a hardenedcondition, for example, PMMA or other bone cements and fillers. In anexemplary embodiment of the invention, the material is provided in a kitthat includes a timer and/or a viscometer, so that an operator canestimate the workability and viscosity of the material and itsusefulness for height restoration without leakage. Optionally, the timeincludes a temperature senor and provides an estimate of workabilitytime based on the temperature and the time the components of the PMMAwere mixed.

In an exemplary embodiment of the invention, a setting material isformulated to have a high viscosity for a working window of significantduration, for example, 2, 4, 5, 8, 10 or intermediate or more minutes.

In an exemplary embodiment of the invention, the following formulationis used: a set of beads formed of PMMA/Styrene of diameter 10-200microns and an amount of 20 cc MMA per 9.2 grams beads. In an exemplaryembodiment of the invention, MMA solvates and/or encapsulates the beadsand the viscosity of the mixture remains high, at the beginning due tothe solvation and friction between the beads and later, as the beadsdissolve, due to the progressing of polymerization. The beads may alsobe provided in a mixture comprising a range of sizes. It should be notedthat the properties of the materials may be selected to improve aviscosity working window, even if strength of the final cement iscompromised.

In an exemplary embodiment of the invention, the working viscosity isset by selecting the bead size and/or material ratios.

Additional Implant Devices

Optionally, an implant is also injected into the vertebra, for example,before, during or after injection of the material. Exemplary implantsare metal or polymer cage or intra ventricular devices and enclosingmesh or solid bags or balloons. Optionally, bone graft is injected.Optionally, where an implant is provided, the material is extrudedthrough the implant, for example from an axial section thereof in aradial direction.

Optionally, devices such as described in PCT applicationsPCT/IL00/00458; PCT/IL00/00058; PCT/IL00/00056; PCT/IL00/00055;PCT/IL00/00471; PCT/IL02/00077; PCT/IL03/00052; and PCT/IL2004/000508,PCT/IL2004/000527 and PCT/IL2004/000923, the disclosures of which areincorporated herein by reference, are used.

Optionally, the material is extruded into a performed cavity, forexample a cavity formed using an inflatable balloon. Optionally, thematerial is extruded into an inter-vertebral space, for example adisc-space.

Optionally, a material which sets to a hardened condition, for example,PMMA is co-extruded with or extruded before or after material which doesnot so set. Optionally, the setting material comprises less than 60% ofthe material, for example, less than 40%, less than 20% or intermediatevalues.

Other Tissue and General

While the above application has focused on the spine, other tissue canbe treated as well, for example, compacted tibia plate and other boneswith compression fractures and for tightening implants, for example, hipimplants or other bone implants that loosened, or during implantation.Optionally, for tightening an existing implant, a small hole is drilledto a location where there is a void in the bone and material is extrudedinto the void.

It should be noted that while the use in bones of the above methods anddevices provide particular advantages for bone and vertebras inparticular, optionally, non-bone tissue is treated, for example,cartilage or soft tissue in need of tightening. Optionally, thedelivered material includes an encapsulated pharmaceutical and is usedas a matrix to slowly release the pharmaceutical over time. Optionally,this is used as a means to provide anti-arthritis drugs to a joint, butforming a void and implanting an eluting material near the joint.

It will be appreciated that the above described methods of implantingand treating may be varied in many ways, including, changing the orderof steps, which steps are performed more often and which less often, thearrangement of elements, the type and magnitude of forces applied and/orthe particular shapes used. In particular, various tradeoffs may bedesirable, for example, between applied forces, degree of resistance andforces that can be withstood. Further, the location of various elementsmay be switched, without exceeding the spirit of the disclosure, forexample, the location of the power source. In addition, a multiplicityof various features, both of method and of devices have been described.It should be appreciated that different features may be combined indifferent ways. In particular, not all the features shown above in aparticular embodiment are necessary in every similar exemplaryembodiment of the invention. Further, combinations of the above featuresare also considered to be within the scope of some exemplary embodimentsof the invention. In addition, some of the features of the inventiondescribed herein may be adapted for use with prior art devices, inaccordance with other exemplary embodiments of the invention. Theparticular geometric forms used to illustrate the invention should notbe considered limiting the invention in its broadest aspect to onlythose forms, for example, where a cylindrical tube is shown, in otherembodiments a rectangular tube may be used. Although some limitationsare described only as method or apparatus limitations, the scope of theinvention also includes apparatus programmed and/or designed to carryout the methods.

Also within the scope of the invention are surgical kits which includesets of medical devices suitable for implanting a device or material andsuch a device. Section headers are provided only to assist in navigatingthe application and should not be construed as necessarily limiting thecontents described in a certain section, to that section. Measurementsare provided to serve only as exemplary measurements for particularcases, the exact measurements applied will vary depending on theapplication. When used in the following claims, the terms “comprises”,“comprising”, “includes”, “including” or the like means “including butnot limited to”.

It will be appreciated by a person skilled in the art that the presentinvention is not limited by what has thus far been described. Rather,the scope of the present invention is limited only by the followingclaims.

The invention claimed is:
 1. A composite tool for accessing bone,comprising: an elongate body, having: a head having a distal tipconfigured to penetrate bone, the head being disposed on a distal end ofthe elongate body; at least one aperture formed in a sidewall of theelongate body proximal to the distal end and being configured to extrudematerial radially therethrough and into bone; a lumen adapted to delivermaterial to the aperture; and a guidewire channel formed within at leasta portion of the elongate body; wherein the guidewire channel iscollapsible in response to pressurizing material to be delivered throughthe lumen.
 2. The tool according to claim 1, further comprising a sourceof material under pressure coupled to a proximal portion of the elongatebody for delivering the material into the lumen.
 3. The tool accordingto claim 2, wherein the source of material is a hydraulic source.
 4. Thetool according to claim 2, wherein the material comprises at least onematerial adapted to function in a capacity other than as a structuralsupport.
 5. The tool according to claim 1, wherein the elongate body andthe head are integrally formed.
 6. The tool according to claim 2,wherein the pressure is at least 40 atmospheres.
 7. The tool accordingto claim 2, wherein the pressure is at least 100 atmospheres.
 8. Thetool according to claim 1, wherein the elongate body comprises aplurality of extrusion apertures formed in a sidewall thereof adapted toextrude material into bone.
 9. The tool according to claim 2, whereinthe material comprises PMMA bone cement.
 10. The tool according to claim9, wherein when the material is delivered into the lumen of the elongatebody, the material has a viscosity between 600 and 1800 Pascal-secondsfor at least 5 minutes.
 11. The tool according to claim 1, furthercomprising a source of material under pressure coupled to a proximalportion of the elongate body, the material comprising PMMA bone cement.12. The tool according to claim 11, wherein when the material isdelivered into the lumen of the elongate body, the material has aviscosity between 600 and 1800 Pascal-seconds for at least 5 minutes.